Professor Alexis Thomson has added to the many kindnesses I have received at his hands by writing the Introduction which immediately precedes this Preface, and I wish to express my sincere thanks to him for such a valuable addition to the book. From Mr David Wallace, F.R.C.S.E., I have received much valuable help and guidance in anæsthetic matters. It was largely due to his kindly assistance and moral support that I was encouraged to persevere with my early attempts to use nitrous oxide and oxygen in major surgery. The hints which are given in connection with Genito-Urinary Surgery are also derived from him. The chapters upon Local and Spinal Anæsthesia are entirely the work of Mr Wood, to whom I must express my gratitude for the admirable way in which he has done the work. I must also thank Dr Torrance Thomson most sincerely for his useful contribution in chapter X, which constitutes a complete monograph upon Intratracheal Anæsthesia. To Dr Wm. Guy I am indebted for the photographs which appear in the book, and I must express my sincere gratitude to him for the trouble he has taken in the matter. Much thanks are also due to the following firms who have been kind enough to lend illustrative blocks:--Messrs Claudius Ash & Co. Ltd., G. Barth & Co., De Trey & Co., J. Gardner & Son, Allen & Hanbury’s Ltd., Meyer & Phelps, Coxeter & Son, Down Bros., Ltd., Krohne & Sesemann, and Mr J. H. Montague. Lastly, I must express my high appreciation of the courtesy which the publishers have shown to me, and of their generosity in the matter of illustrations. J. STUART ROSS. _October 1919._ Handbook of Anæsthetics. CHAPTER I. PHYSIOLOGICAL ACTION OF ANÆSTHETIC DRUGS. Every anæsthetic drug has certain pharmacological peculiarities of its own, but all have much in common, and it is to these common features we shall first direct our attention. Reaching the blood stream by absorption from the lung alveoli, the drug enters into loose combination with the red blood corpuscles; a small proportion only is carried in the plasma. Within the corpuscles it must of necessity displace a certain proportion of the oxygen normally carried: this factor is of great importance only in the case of nitrous oxide gas, which readily displaces the larger part of the normal oxygen content. In the case of other anæsthetics, the same process occurs; but to a less extent. Detailed figures of the extent to which the blood gases are altered in various stages of chloroform anæsthesia will be found in Appendix III.